Background: This survey followed a cohort of patients with chronic psychosis recruited from five catchment areas (DSMs) of the Sardinian community mental health services. The objective was to examine whether the amount of resources in the different sites may be a determinant of the outcomes. Methods: Naturalistic follow-up study on 309 consecutive users with diagnosis of schizophrenic disorder, schizoaffective disorder, bipolar affective disorder with psychotic symptoms (DSM-IV TR) of five Sardinian community mental health services. Mental state and clinical symptoms along with functioning were assessed using semi-structured clinical interviews (ANTAS), Clinical Global Impression Severity Scale (CGI-S), Global Assessment of Functioning Scale (GAF) and Health of the Nation Outcome Scales (HONOS). Assessments were conducted at the beginning of the study and after one year. Results: The proportion of professionals working in all DSMs participating in the study was found lower than the national Italian standard (0.7 vs 1.0 per 1,500 inhabitants). Follow-up revealed significant differences between DSMs in the improvement of the Honos scores (F = 5.932, p = 0.000). These differences correlate with the improvement of resources in terms of number of professionals during, and one year prior, to the trial. Conclusions: The study shows that mental health services provided in the public sector in Sardinia are still very resource-poor, at least in terms of human resources. Our findings suggest that mental health service resources influence outcomes as regards the social functioning of users. We urge policy makers to take these observations into account when planning future services.